Expandable underreamer



Feb. 4, 1969 B. H. FUCHS I EXPANDABLE UNDERREAMER Shet Filed Nov. 25,1966 JANE/4702. BENJAMIN H. Z Z/CH5 y M fi/aml firromvsys.

B. H. FUCHS EXPANDABLE UNDERREAMER Feb. 4, 1969 Sheet Filed Nov 25,19,66

I NVENTOR. BENJAMIN H. 1 00/5 flrrakwsya KQu m i Mama! I United StatesPatent 3,425,500 EXPANDABLE UNDERREAMER Benjamin H. Fuchs, 3842 RoseAve., Long Beach, Calif. 90807 Filed Nov. 25, 1966, Ser. No. 597,075U.S. Cl. 175-269 Int. Cl. E21b 9/26 1 Claim ABSTRACT OF THE DISCLOSUREThe present invention relates generally to the well drilling art, and itrelates more particularly to underreamers for enlarging well holes andto novel wash means embodied therein for keeping the underreamer cuttersclean during the operation.

Underreamers are employed extensively for enlarging portions of the wellbore in oil and gas wells for various purposes, as for example toprovide clearance for running casing, to obtain adequate annular spacein the hole for cementing, to enlarge zones for gravel pack completion,and for other purposes. Conventional practice for removing the cuttingsand washing the underreamer cutter cones is merely to pump the drillingfluid down through the underreamer into the region of the hole below theunderreamer, the fluid washing upwardly past the cutters. However, thecutters are in effect operating on a ledge, and the drilling fluid whichis thus released into the hole below the cutters tends to flow upwardlypast this ledge without applying any concentrated washing flow at thecritical area of cutting on the ledge, the fluid which does flow intothe cutting area merely being a backwash which is not suflicientlyconcentrated or under sufficient pressure to properly clean the cones.Accordingly, with such conventional washing the sand and cuttings tendto ball up on the cutting ledge, requiring that portions of theformation 'be recut over and over again, thus greatly impairing thecutting efliciency of the tool and resulting in a reduction in the rateat which a hole can be enlarged and more frequent replacement of thecutter cones.

While there have been prior art attempts to solve this problem, theyhave also been generally unsatisfactory. For example, one means whichhas been employed in an attempt to obtain improved washing ofunderreamer cutters is to employ upwardly directed spray jets on thetool at a point below the cutters, with a jet of drilling fluid beingdirected upwardly along the outside of the tool toward each of thecutters. However, these upwardly directed spray jets are released in therelatively small part of the hole below the cutting ledge, so that theprimary force of these jets is not directed against the cutters wherethey are performing their work on the ledge.

In view of these and other problems in the art, it is an object of thepresent invention to provide a novel underreamer wash system whereindrilling fluid is jetted under pressure directly into the region of thecutting plane of the cutters so that the washing action of the drillingfluid is fully effective on the ledge where the cutters are performingtheir work.

Another object of the invention is to provide a novel underreamer washsystem of the character described wherein fluid jet outlets are disposedon the underreamer immediately above the cutters and are arranged todirect pressurized jet streams of drilling fluid directly to the cuttingplane of the cutters proximate the diameter of cutter operation.

A further object of the present invention is to provide an underreamerwash system of the character described wherein the jet orifices arepositioned on the underreamer body intermediate the cutter arms andimmediately above the cutter cones, the orifices directing pressurizedjet streams of drilling fluid in a downwardly and outwardly divergingdirection against the ledge where the cutters are operating, whereby thedrilling fluid is placed without interference from the cutter arms orother structure in the optimum position for effectively washing thecutters.

Further objects and advantages of this invention will appear during thecourse of the following part of this specification, wherein the detailsof construction and mode of operation of a preferred embodiment aredescribed with reference to the accompanying drawings, in which:

FIGURE 1 is a vertical, axial section, with portions in elevation,illustrating an underreamer embodying the present invention, with thecutter arms disposed in their collapsed or withdrawn positions.

FIGURE 2 is a horizontal section taken on the line 2-2 in FIGURE 1.

FIGURE 3 is a horizontal section taken on the line 33 in FIGURE 1.

FIGURE 4 is a vertical, axial section, with portions in elevation,similar to FIGURE 1, but illustrating the underreamer of FIGURE 1, 2 and3 in operation enlarging a bore, with the cutter arms in their extended,operative positions.

FIGURE 5 is a fragmentary elevational view showing the lower portion ofthe underreamer that is shown in FIGURES 1 to 4.

FIGURE 6 is an enlarged, fragmentary elevational view, taken on the line66 in FIGURE 4, illustrating one of the jets.

Referring to the drawings, an expandable underreamer 10 according to thepresent invention includes a generally tubular, elongated body 12 whichis threadedly connected to a suitable tubular top sub 14.

Three cutter arms 16 are longitudinally arranged at regularly spacedintervals about the tubular body 12 in the lower portion thereof, thearms '16 being supported in respective elongated slots '18 in the body'12. The cutter arms 16 are pivotally supported proximate their upperends on respective horizontal support pins 20 which are mounted in thebody 12, and arcuate upper ends of the cutter arms 16 are seated incomplementary recesses in respective arm retainers 22 which are boltedor otherwise secured to the body '12 and serve as thrust bearing meansfor applying drill string weight to the cutters. Conventional cuttercones 24 are rotatably mounted at the lower ends of the respectivecutter arms 16.

Axially centered within the tubular body 12 is a wash barrel 28 which isslidably supported near its lower end in a bushing 30, and which has apiston 32 secured to its upper end portion, the piston 32 being slidablewithin an enlarged cylinder 34 in the tubular body 12. In theinoperative position of the underreamer as shown in FIGURE 1, the washbarrel 28 and piston 32 are in an uppermost position, and in the fullyoperative position of the tool as illustrated in FIGURE 4 the washbarrel 28 and piston 32 are in a lower rn'ost position which is definedby engagement of the piston 32 against an upwardly facing shoulder 36 atthe bottom of the enlarged cylinder 34. An intermediate enlargement 38in the bore of body 12 provides seating for a helical spring 40 whichbiases the piston and wash barrel toward their uppermost positions asillustrated in FIGURE 1. The piston 32 and wash barrel 28 are normallyin the uppermost position of FIGURE 1, but ma be selectively moveddownwardly to the position of FIG- URE 4 by the introduction of drillingfluid under pressure through the sub 14 and into the cylinder 34.

Three cam-s 42 project radially outwardly from the wash barrel 28, thecams 42 being integrally connected to the wash barrel 28 as by weldingand being regularly spaced thereabout so that each of the cams 42 is inalignment with a respective one of the cutter arms 16. The arms 16 havegenerally radially inwardly facing cam follower surfaces 44 thereonwhich are engaged by the respective cams 42 upon downward movement ofthe cams 42 to move the cutter arms 16 from their retracted positions asillustrated in FIGURE 1 outwardly to their extended, operative positionsas illustrated in FIGURE 4. The cam follower surfaces 44 terminate attheir lower ends in respective cam ledges 46 against which the cams 42abut for holding the cutter arms 16 in the fully extended or full swingposition illustrated in FIGURE 4.

Three fluid passages 48 extend longitudinally through the body 12 fromrespective entrances 50 located in the upper part of the enlargedcylinder 34 to respective jet orifices or outlets 52 that are located asclose as is practical above the cutter cones 24. Each of the jetorifices 52 opens into a recess in the outer surface of body 12 that isformed by a downwardly and outwardly curving guide surface 54. These jetguide surfaces 54 have been found to be a convenient means for directingthe jet flow of pressurized fluid in a downwardly and outwardlydiverging stream. Accordingly, each of the jet guide surfaces 54 may beconsidered as actually forming a part of its respective jet orifice 52for the purpose of the present invention.

Preferably, the fluid passages 48 are circumferentially disposed in thebody 12 intermediate the cutter arms 16 as best illustrated in FIGURES 2and 3. Similarly, the jet orifices 52 are circumferentially arrangedabout the body 12 intermediate the cutter arms 16 and immediately abovethe cutter cones 24. Thus, when the tool is rotating during a cuttingoperation to ream a portion of a hole 56 out to an enlarged portion 58as in FIGURE 4, each of the cutting cones 24 is led by a jet stream 60which is directed generally into the region of the cutting plane, and inthis manner the jet stream 60 will provide a full high-velocity washingflow directly in the region of the cutting ledge where it is mosteffective, the flow being unimpaired by any stricture on the underreameror by the ledge itself.

In the inoperative position of the underreamer as it is being loweredthrough the hole to a desired region of operation, drilling fluid willnot be pumped through the sub 14 into the cylinder 34, and hence thebiasing force of spring 40 will hold the piston 32, wash barrel 28 andcams 42 in their uppermost positions as illustrated in FIGURE 1, thesepositions being defined by engagement of the earns 42 against shoulders64 in the cutter arms 16. In this inoperative condition of theunderreamer the cutter arms 16 are held in their collapsed positions asshown in FIGURE 1 by gravity, and also by the spring biased engagementof the cams 42 against the shoulders 64 in the cutter arms.

When the tool is at the desired position in the hole to commencereaming, the tool is rotated and drilling fluid is introduced underpressure through the sub 14 into the cylinder 34. Some of this drillingfluid will pass on downwardly through the wash barrel 28 and thencethrough the hollow lower portion of the body 12 into the hole below theunderreamer, and the flow of this fluid back upwardly around the toolwill wash away the cuttings which are relatively free and which arefreed by the jet streams provided according to the present invention.Preferably, there is a constriction 62 in the wash pipe which serves tobuild up fluid pressure in the cylinder 34 so as to more effectivelyactuate the cuttersand provide high pressure and velocity to the jetstreams 60 of the invention.

The fluid pressure in cylinder 34 will force piston 32 downwardly fromthe position of FIGURE 1 to the position of FIGURE 4, which will in turnmove wash barrel 28 and earns 42 downwardly so as to swing the cutterarms 16 outwardly to their operative positions. The pressurized fluid incylinder 34 will also cause fluid to be forced through the fluidpassages 48 from entrances 50, and thence out through the jet orificesor outlets 52 which direct the jet streams 60 divergently downwardly andradially outwardly to the general region of the cutting plane of thecutters 24.

When the reaming operation is completed the fluid pressure is relieved,and this stops the jet streams 60 and also permits the spring to returnthe piston 32, wash barrel 28 and cams 42 back to their positions ofrepose as illustrated in FIGURE 1, collapsing the cutter arms 16 backinto the confines of the respective slots 18 in the body of theunderreamer.

While the instant invention has been shown and described herein in whatis conceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of theinvention, which is therefore not to be limited to the details disclosedherein, but is to be accorded the full scope of the claim so as toembrace any and all equivalent devices.

I claim:

1. An expandable underreamer adapted to be suspended from a drillstring, said underreamer comprising an elongated, generally cylindricalbody having three cutter members regularly peripherally spaced aboutsaid body at substantially the same axial position, said cutter memberseach including a cutter arm extending downwardly from a pivotalconnection with the body and terminating at its lower end in a rollercutter, the cutter arms being recessed within respective elongated slotsin the body in their inoperative positions and swinging outwardly totheir operative positions, hydraulic actuating means responsive todrilling fluid pressure from the drill string for moving said cuttermembers from their inoperative positions to their operative positionscomprising a hydraulic cylinder in the body spaced above said cuttermembers and receiving drilling fluid under pressure from the drillstring, a piston in said cylinder movable in response to drilling fluidpressure, cam means connected to said piston and cooperating camfollower means connected to said cutter members, and means for washingthe region proximate said roller cutters during operation thereofcomprising three regularly spaced fluid ports in the body of the toolcommunicating with said hydraulic cylinder above said piston, threefluid passages extending longitudinally through the body of the toolfrom the respective said fluid ports at their upper ends to threerespective jet orifices at the lower ends thereof, said three fluidpassages and said jet orifices being regularly circumferentially spacedabout the body of the tool intermediate said three cutter members, withsaid jet orifices being disposed intermediate the cutter armssubstantially 5 immediately above the roller cutters, the application ofdrilling fluid pressure from the drill string substantiallysimultaneously initiating jet streams from said jet orifies and movingsaid piston downwardly in said cylinder so as to cause said cuttermembers to be moved from their inoperative positions to their operativepositions. 5

References Cited UNITED STATES PATENTS 1,857,616 5/1932 Baker 175269 10Santiago 175-269 Ba'rg 175269 Baker 175267 Sharp 175269 CHARLES E.OCONNELL, Primary Examiner.

R. E. FAVREAU, Assistant Examiner.

